linux-stable.git/arch/powerpc/kernel/traps.c, branch linux-3.10.y

powerpc: Fix context switch DSCR on POWER8

2013-08-15T05:59:05+00:00

commit 2517617e0de65f8f7cfe75cae745d06b1fa98586 upstream.

POWER8 allows the DSCR to be accessed directly from userspace via a new SPR
number 0x3 (Rather than 0x11.  DSCR SPR number 0x11 is still used on POWER8 but
like POWER7, is only accessible in HV and OS modes).  Currently, we allow this
by setting H/FSCR DSCR bit on boot.

Unfortunately this doesn't work, as the kernel needs to see the DSCR change so
that it knows to no longer restore the system wide version of DSCR on context
switch (ie. to set thread.dscr_inherit).

This clears the H/FSCR DSCR bit initially.  If a process then accesses the DSCR
(via SPR 0x3), it'll trap into the kernel where we set thread.dscr_inherit in
facility_unavailable_exception().

We also change _switch() so that we set or clear the H/FSCR DSCR bit based on
the thread.dscr_inherit.

Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc: Wire up the HV facility unavailable exception

2013-07-25T21:07:21+00:00

commit b14b6260efeee6eb8942c6e6420e31281892acb6 upstream.

Similar to the facility unavailble exception, except the facilities are
controlled by HFSCR.

Adapt the facility_unavailable_exception() so it can be called for
either the regular or Hypervisor facility unavailable exceptions.

Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc: Rename and flesh out the facility unavailable exception handler

2013-07-25T21:07:21+00:00

commit 021424a1fce335e05807fd770eb8e1da30a63eea upstream.

The exception at 0xf60 is not the TM (Transactional Memory) unavailable
exception, it is the "Facility Unavailable Exception", rename it as
such.

Flesh out the handler to acknowledge the fact that it can be called for
many reasons, one of which is TM being unavailable.

Use STD_EXCEPTION_COMMON() for the exception body, for some reason we
had it open-coded, I've checked the generated code is identical.

Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc: Fix emulation of illegal instructions on PowerNV platform

2013-06-15T02:24:11+00:00

Normally, the kernel emulates a few instructions that are unimplemented
on some processors (e.g. the old dcba instruction), or privileged (e.g.
mfpvr).  The emulation of unimplemented instructions is currently not
working on the PowerNV platform.  The reason is that on these machines,
unimplemented and illegal instructions cause a hypervisor emulation
assist interrupt, rather than a program interrupt as on older CPUs.
Our vector for the emulation assist interrupt just calls
program_check_exception() directly, without setting the bit in SRR1
that indicates an illegal instruction interrupt.  This fixes it by
making the emulation assist interrupt set that bit before calling
program_check_interrupt().  With this, old programs that use no-longer
implemented instructions such as dcba now work again.

CC: 
Signed-off-by: Paul Mackerras 
Signed-off-by: Benjamin Herrenschmidt

powerpc/tm: Abort on emulation and alignment faults

2013-05-31T22:29:22+00:00

If we are emulating an instruction inside an active user transaction that
touches memory, the kernel can't emulate it as it operates in transactional
suspend context.  We need to abort these transactions and send them back to
userspace for the hardware to rollback.

We can service these if the user transaction is in suspend mode, since the
kernel will operate in the same suspend context.

This adds a check to all alignment faults and to specific instruction
emulations (only string instructions for now).  If the user process is in an
active (non-suspended) transaction, we abort the transaction go back to
userspace allowing the HW to roll back the transaction and tell the user of the
failure.  This also adds new tm abort cause codes to report the reason of the
persistent error to the user.

Crappy test case here http://neuling.org/devel/junkcode/aligntm.c

Signed-off-by: Michael Neuling 
Cc:  # v3.9
Signed-off-by: Benjamin Herrenschmidt

powerpc: Exception hooks for context tracking subsystem

2013-05-14T06:00:19+00:00

This is the exception hooks for context tracking subsystem, including
data access, program check, single step, instruction breakpoint, machine check,
alignment, fp unavailable, altivec assist, unknown exception, whose handlers
might use RCU.

This patch corresponds to
[PATCH] x86: Exception hooks for userspace RCU extended QS
  commit 6ba3c97a38803883c2eee489505796cb0a727122

But after the exception handling moved to generic code, and some changes in
following two commits:
56dd9470d7c8734f055da2a6bac553caf4a468eb
  context_tracking: Move exception handling to generic code
6c1e0256fad84a843d915414e4b5973b7443d48d
  context_tracking: Restore correct previous context state on exception exit

it is able for exception hooks to use the generic code above instead of a
redundant arch implementation.

Signed-off-by: Li Zhong 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Emulate non privileged DSCR read and write

2013-05-05T23:25:35+00:00

POWER8 allows read and write of the DSCR in userspace. We added
kernel emulation so applications could always use the instructions
regardless of the CPU type.

Unfortunately there are two SPRs for the DSCR and we only added
emulation for the privileged one. Add code to match the non
privileged one.

A simple test was created to verify the fix:

http://ozlabs.org/~anton/junkcode/user_dscr_test.c

Without the patch we get a SIGILL and it passes with the patch.

Signed-off-by: Anton Blanchard 
Cc: 
Signed-off-by: Benjamin Herrenschmidt

Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

2013-02-25T23:41:43+00:00

Pull module update from Rusty Russell:
 "The sweeping change is to make add_taint() explicitly indicate whether
  to disable lockdep, but it's a mechanical change."

* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  MODSIGN: Add option to not sign modules during modules_install
  MODSIGN: Add -s  option to sign-file
  MODSIGN: Specify the hash algorithm on sign-file command line
  MODSIGN: Simplify Makefile with a Kconfig helper
  module: clean up load_module a little more.
  modpost: Ignore ARC specific non-alloc sections
  module: constify within_module_*
  taint: add explicit flag to show whether lock dep is still OK.
  module: printk message when module signature fail taints kernel.

powerpc: Hook in new transactional memory code

2013-02-15T06:02:23+00:00

This hooks the new transactional memory code into context switching, FP/VMX/VMX
unavailable and exception return.

Signed-off-by: Matt Evans 
Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Routines for FP/VSX/VMX unavailable during a transaction

2013-02-15T06:02:23+00:00

We do lazy FP but not lazy TM (ie. userspace starts with MSR TM=1 FP=0).  Hence
if userspace does an FP instruction during a transaction, we'll take an
fp unavailable exception.

This adds functions needed to handle this case.  We have to inject the current
FP state into the checkpoint so that the hardware can decide what to do with
the transaction.  We can't inject only the FP so we have to do a full treclaim
and recheckpoint to inject just the FP state.  This will cause the transaction
to be marked as aborted by the hardware.

This just add the routines needed to do this for FP, VMX and VSX.  It doesn't
hook them into the rest of the code yet.

Signed-off-by: Matt Evans 
Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt